Capacitors employ thermoplastic dielectric thin film polymers, such as polypropylene (PP), polyethylene terephthalate (PET), polycarbonate, polyethylene-2,6-naphthalate, polyvinylidene difluoride (PVDF), polyphenylene oxide, polytetrafluoroethylene and polyphenylene sulfide, either metallized or maintained between metal foil electrodes. Metalized film capacitors are used extensively in a broad range of electrical and electronic equipment that include motor run and motor start circuits for air conditioners, fluorescent and high intensity light ballasts, power supplies, telecommunication equipment, instrumentation, and medical electronics. In many of these applications, the metallized capacitors are used to store energy.
U.S. Pat. No. 8,611,068 describes a multilayer coextrusion process of polymer materials for the production of dielectric films. The patent discloses dielectric multilayer polymer films comprising alternating layers of polymers with different dielectric properties creating interfaces between the layers that delocalizes the charge and improves the dielectric properties. The patent discloses using two or more polymers or blends thereof, miscible or immiscible, in multilayered films. Subsequent stretching of the films is also taught to improve the dielectric properties.